Molybdenum disulfide (MoS2) is usually recovered from molybdenite ore obtained from “primary” mine sites, although it can be recovered from secondary or by-product molybdenite obtained from “non-primary” mine sites as well. For example, secondary molybdenite may be obtained from copper mines, wherein the secondary molybdenite is typically combined with copper-containing materials (e.g., copper sulfide). In such cases, molybdenum disulfide concentrate is obtained as a by-product from copper sulfide-molybdenum disulfide separation processes.
Broadly speaking, molybdenite ore consists of silicified granite compositions having deposits of soft, black, and hexagonal MoS2 crystalline structures widely dispersed therein (e.g., in an average concentration of only about 0.03-0.6% by weight of the entire ore body). One of the largest sources of MoS2-containing ore (e.g., molybdenite) is the Henderson molybdenum mine near Empire, Colo. (US), currently operated by the Climax Molybdenum Company, although other mine sites throughout the world are able to produce large amounts of this material as well. The Henderson mine site is characterized as a “primary” mine and is capable of producing large amounts of molybdenite ore.
In a typical processing operation, the molybdenite ore is initially subjected to a physical grinding process in which the ore is reduced in size to a plurality of small particles (e.g., having a typical particle size of about 100 U.S. mesh or less). The ore particles are then further treated to remove the desired MoS2 therefrom. This treatment step may be accomplished using a variety of techniques, including froth flotation extraction procedures that employ various hydrocarbon compositions and wetting agents known in the art for this purpose. As a result, the desired MoS2 may be effectively separated from ore-based waste materials (i.e., “gangue”), such as silica, silicates, clays, and other unwanted materials. The desired MoS2 compositions will, by virtue of their minimal weight and density levels compared with the gangue, be readily isolated in the flotation froth.
The resulting molybdenum disulfide concentrate (i.e., from either primary or secondary sources, as noted above) may be dried and sized (e.g., by grinding and subsequent classification steps) to produce a molybdenum disulfide powder product having the desired grade and particle size. Exemplary grades of molybdenum disulfide include “technical,” “technical fine,” and “superfine” grades, although other grades are known and commercially available. Technical grades of molybdenum disulfide typically comprise about 98% (by weight) molybdenum disulfide, with the balance comprising various amounts of iron, molybdenum trioxide, water, oil, and carbon, depending on a wide variety of factors.
Molybdenum disulfide powders of the type just described may be used in any of a wide variety of products and for a wide variety of purposes. For example, molybdenum disulfide powders are commonly used as lubricants, e.g., either in “dry” form or when combined with a variety of oils and greases. Molybdenum disulfide may also be used to form molybdenum disulfide coatings on any of a wide range of articles, typically to enhance the lubricity of such materials. Molybdenum disulfide powders may also be combined with various materials, such as metals, metal alloys, resins, and polymers, to enhance the properties thereof.